I am a relative noob to leatherworking. Maybe about 4 months expirience. I have been using a box cutter for making my holsters. It works, but the blades don't stay sharp for long and the cuts seem like they leave something to be desired. I have been wondering about a round knife. Are they worth the investment, or will they return the same results as a box knife? Also what size(s) are the best to use for holsters. Can I use one or do I need a couple different sized blades?